China’s world record breaking Sun Yang, back in action at the FINA World Championships. Sun, back in the blocks for the men’s 400m freestyle as he looked to add the World title to the Olympic crown in the distance he grabbed last summer in London.

The men’s 400 free brought the first opportunity for the young Chinese talent to cement his place as the premier distance freestyler in the world. And the 21-year-old, would dominate the event from the beginning just as he did in the London 2012 final.

After 200m, Sun was on track to break Paul Biedermann’s world record of 3-minutes 40.07 seconds, set four years ago at the Rome world championships, where the German used the now-banned high-tech suits.

While Sun faded a bit from that world record pace during the third 100 metres, no one would mount a serious challenge to the Chinese. Sun won the 800-meter and 1,500-meter freestyles at the 2011 Shanghai World Championships, but finished second to South Korean Park Tae-Hwan in the 400-meters. This time around, Sun had no peers in the pool, turning it on at the finish to win in a romp. He finished with a time of 3 minutes, 41.59 seconds, to back up his win in London.

After the race, the 21-year-old couldn’t hide his emotions on the podium as he overcame a few tough months, that saw Sun deal with a controversy involving his former coach which also impacted his preparation heading into the Barcelona World’s.

Sun said, "I didn’t have my best training over the last two months. I admit I’m not as strong as I was at the London Olympics. I tried hard to compete, and I adjusted my training to be my best in the final month leading up to the tournament. I thank my coach and all the people who support me."